The disruption caused by the
US-Israel-Iran war in the Gulf region has not just rerouted ships, it has also quietly revived a legal provision that most cargo owners rarely think about, until something goes wrong.
Global carriers such as MSC, Maersk, CMA CGM and Hapag-Lloyd have told customers they may discharge containers at ports other than the agreed destination, passing on the cost, according to a report by the Financial Times. The authority to do this comes from a long-standing clause embedded in shipping contracts, with origins in 19th-century maritime law.
It is an old rule but is now being used in a new crisis. And it matters because even today, nearly 90 per cent of global trade moves by sea, with roughly 5 per cent passing through the Strait of Hormuz. Following the latest strikes, about 3,200 vessels are now held up across the Gulf.
Once rerouting, delays, and port disruptions are factored in, cargo owners are also facing added land transport, storage, handling, and import-related charges. These unplanned costs can push the final bill into the low four-figure range per container above the original quote.
What is the ‘19th-century rule’ in shipping contracts?
In modern shipping, cargo moves under a document called a bill of lading. This is both a receipt and a contract between the shipper and the carrier.
Most bills of lading include what is known as a “liberties clause” or “deviation clause”, which allows the carrier to change the voyage if conditions make the original route unsafe or impractical.
The clause can permit the carrier to change the route, delay the voyage, or discharge cargo at a different port.
These provisions trace back to 19th-century maritime practice, when voyages were more exposed to war, piracy, and weather risks, and shipmasters needed authority to act without breaching contract terms.
That basic legal logic has carried forward into today’s standard shipping contracts.
How did modern maritime contract rules evolve historically?
In the late 18th and early 19th centuries, English courts began to move the bill of lading beyond its narrow function merely as a receipt. As overseas trade expanded, mercantile practice pushed courts to recognise it as a document that could transfer rights in the cargo itself.
The shift was cemented in Lickbarrow v Mason (1793). The ruling clarified that when a bill of lading is endorsed in blank, it can pass ownership of the goods to a subsequent holder. In effect, once such a transfer takes place, the original seller cannot reclaim the goods in transit if they have already reached a bona fide buyer.
Why are shipping carriers invoking this rule now?
The immediate reason is the disruption caused by the Iranian war around the Gulf and nearby sea lanes. Security risks, including air strikes and the threat of attacks on commercial vessels, have made some routes difficult to operate. At the same time, insurers have tightened conditions for ships entering war-risk zones, and rerouting has increased fuel consumption and transit time.
In such conditions, completing the contracted journey to the named port may not be feasible, and that is where the clause gives carriers a way to limit their exposure by ending the voyage at the nearest workable port.
This is why containers meant for one destination are being discharged elsewhere.
What happens when cargo is discharged at another port?
The cost and responsibility shift to the cargo owner. Once a container is discharged at an alternative port, the consignee typically has to arrange onward transport to the final destination, storage and handling at the interim port, and any applicable import or clearance charges.
These costs are not part of the original freight quote. They arise after the deviation.
In effect, the contract allows the carrier to complete its obligation at a different point, with the remaining logistics falling on the customer.
During stable, relatively peaceful conditions, shipping routes are fixed and predictable, and deviating from them creates delays, adds cost, and risks damaging commercial relationships.
For that reason, these clauses usually remain in the background, as part of the legal framework, but not part of day-to-day operations.
Why does this matter for global trade now?
The invocation of the 19th-century maritime rule changes how risk is distributed across the supply chain because when routes are stable, most of the risk sits with the carrier until cargo reaches the agreed port. However, when disruption forces deviations, part of that risk shifts to cargo owners, often suddenly and without much room to renegotiate.
With a large share of global trade moving by sea, even limited disruptions can create a domino effect in pricing, delivery timelines, and inventory planning.
 "What is the '19th-century rule' shipping firms are invoking amid Iran war?")
